Semiconductor devices are manufactured using multi-purpose semiconductor fabrication tools. Because of the ever-decreasing dimensions of current semiconductor devices, these tools fabricate devices according to strict specifications. Being multi-purpose, these tools generate ions of different species for different fabrication steps, using beams that span a wide range of energies. Capable of fabricating small-geometry devices, these tools have strict scanning dimensions. They also perform mass analyses to reduce contamination and include a special module to neutralize the collected charge on a substrate. Because these tools are so complex and their requirements are so stringent, their output is relatively small, only about 200 wafers per hour.
FIG. 1 show a prior art implant system 100 for implanting substrates as one step in fabricating a semiconductor device. Multiple wafers are introduced into the system 100 through twin load locks 105. A multiple gas delivery module 110 contains multiple gases from which n-type and p-type ions (dopants) are extracted. The ions are accelerated by a pre-accelerator 120, which transmits them to a magnet 125 that performs mass analysis to reduce contamination. The ions are then transmitted to a post-accelerator 130 and then on to a charge neutralization module 135. The beam of ions is scanned across the surfaces of multiple wafers 101 using a beam scanning mechanism 140; alternatively, the wafers 101 themselves are moved relative to the beam. A Measurements and Control unit 145 then analyzes the wafers 101.
Because the system 100 must be able to implant different dopants, the operating range of the pre-accelerator 120 and the magnet 125 must be large, generally less than 10 keV to 200 keV-sufficient to implant all the dopant types. The system 100 must also be capable of satisfying the stringent requirements of advanced geometries (smaller than 65 nm). As one example, uniformity requirements of less than 0.5% require multiple beam scans, which reduces system productivity.
A second drawback is that features on the devices vary during different stages of device fabrication. These features cannot withstand the high temperatures or collected charge to which they are exposed. Furthermore, the features themselves can adversely affect the implant beam, such as when an insulating film collects charge during its formation.
With few exceptions, device fabrication requires beams with large power densities and the generation of high temperatures. These limitations in general make prior art fabrication systems complex.